[PATCH v2 07/13] KVM: selftests: add library for creating/interacting with SEV guests

From: Michael Roth <michael.roth@amd.com>
To: <linux-kselftest@vger.kernel.org>
Cc: <kvm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<x86@kernel.org>, Nathan Tempelman <natet@google.com>,
	Marc Orr <marcorr@google.com>,
	"Steve Rutherford" <srutherford@google.com>,
	Sean Christopherson <seanjc@google.com>,
	Mingwei Zhang <mizhang@google.com>,
	Brijesh Singh <brijesh.singh@amd.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Varad Gautam <varad.gautam@suse.com>,
	Shuah Khan <shuah@kernel.org>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	"David Woodhouse" <dwmw@amazon.co.uk>,
	Ricardo Koller <ricarkol@google.com>,
	"Jim Mattson" <jmattson@google.com>,
	Joerg Roedel <joro@8bytes.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "Borislav Petkov" <bp@alien8.de>,
	"H . Peter Anvin" <hpa@zytor.com>,
	Krish Sadhukhan <krish.sadhukhan@oracle.com>,
	Peter Gonda <pgonda@google.com>
Subject: [PATCH v2 07/13] KVM: selftests: add library for creating/interacting with SEV guests
Date: Thu, 16 Dec 2021 11:13:52 -0600	[thread overview]
Message-ID: <20211216171358.61140-8-michael.roth@amd.com> (raw)
In-Reply-To: <20211216171358.61140-1-michael.roth@amd.com>

Add interfaces to allow tests to create/manage SEV guests. The
additional state associated with these guests is encapsulated in a new
struct sev_vm, which is a light wrapper around struct kvm_vm. These
VMs will use vm_set_memory_encryption() and vm_get_encrypted_phy_pages()
under the covers to configure and sync up with the core kvm_util
library on what should/shouldn't be treated as encrypted memory.

Signed-off-by: Michael Roth <michael.roth@amd.com>
---
 tools/testing/selftests/kvm/Makefile          |   9 +-
 .../selftests/kvm/include/x86_64/sev.h        |  44 ++++
 tools/testing/selftests/kvm/lib/x86_64/sev.c  | 245 ++++++++++++++++++
 3 files changed, 297 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/kvm/include/x86_64/sev.h
 create mode 100644 tools/testing/selftests/kvm/lib/x86_64/sev.c

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 412de8093e6c..ccc382a827f1 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -33,8 +33,14 @@ ifeq ($(ARCH),s390)
 	UNAME_M := s390x
 endif
 
+# On some systems the SEV device path may not be present in the standard
+# location, so allow it to be configured via, e.g.:
+#   make TARGETS=kvm SEV_PATH=/path/to/sev_device ...
+SEV_PATH=/dev/sev
+
 LIBKVM = lib/assert.c lib/elf.c lib/io.c lib/kvm_util.c lib/rbtree.c lib/sparsebit.c lib/test_util.c lib/guest_modes.c lib/perf_test_util.c lib/ucall_common.c
 LIBKVM_x86_64 = lib/x86_64/apic.c lib/x86_64/processor.c lib/x86_64/vmx.c lib/x86_64/svm.c lib/x86_64/ucall.c lib/x86_64/handlers.S
+LIBKVM_x86_64 += lib/x86_64/sev.c
 LIBKVM_aarch64 = lib/aarch64/processor.c lib/aarch64/ucall.c lib/aarch64/handlers.S lib/aarch64/spinlock.c lib/aarch64/gic.c lib/aarch64/gic_v3.c lib/aarch64/vgic.c
 LIBKVM_s390x = lib/s390x/processor.c lib/s390x/ucall.c lib/s390x/diag318_test_handler.c
 
@@ -134,7 +140,8 @@ endif
 CFLAGS += -Wall -Wstrict-prototypes -Wuninitialized -O2 -g -std=gnu99 \
 	-fno-stack-protector -fno-PIE -I$(LINUX_TOOL_INCLUDE) \
 	-I$(LINUX_TOOL_ARCH_INCLUDE) -I$(LINUX_HDR_PATH) -Iinclude \
-	-I$(<D) -Iinclude/$(UNAME_M) -I..
+	-I$(<D) -Iinclude/$(UNAME_M) -I.. \
+	-DSEV_DEV_PATH=\"$(SEV_PATH)\"
 
 no-pie-option := $(call try-run, echo 'int main() { return 0; }' | \
         $(CC) -Werror -no-pie -x c - -o "$$TMP", -no-pie)
diff --git a/tools/testing/selftests/kvm/include/x86_64/sev.h b/tools/testing/selftests/kvm/include/x86_64/sev.h
new file mode 100644
index 000000000000..2f7f7c741b12
--- /dev/null
+++ b/tools/testing/selftests/kvm/include/x86_64/sev.h
@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Helpers used for SEV guests
+ *
+ * Copyright (C) 2021 Advanced Micro Devices
+ */
+#ifndef SELFTEST_KVM_SEV_H
+#define SELFTEST_KVM_SEV_H
+
+#include <stdint.h>
+#include <stdbool.h>
+#include "kvm_util.h"
+
+/* Makefile might set this separately for user-overrides */
+#ifndef SEV_DEV_PATH
+#define SEV_DEV_PATH		"/dev/sev"
+#endif
+
+#define SEV_FW_REQ_VER_MAJOR	0
+#define SEV_FW_REQ_VER_MINOR	17
+
+#define SEV_POLICY_NO_DBG	(1UL << 0)
+#define SEV_POLICY_ES		(1UL << 2)
+
+enum {
+	SEV_GSTATE_UNINIT = 0,
+	SEV_GSTATE_LUPDATE,
+	SEV_GSTATE_LSECRET,
+	SEV_GSTATE_RUNNING,
+};
+
+struct sev_vm;
+
+void kvm_sev_ioctl(struct sev_vm *sev, int cmd, void *data);
+struct kvm_vm *sev_get_vm(struct sev_vm *sev);
+uint8_t sev_get_enc_bit(struct sev_vm *sev);
+
+struct sev_vm *sev_vm_create(uint32_t policy, uint64_t npages);
+void sev_vm_free(struct sev_vm *sev);
+void sev_vm_launch(struct sev_vm *sev);
+void sev_vm_launch_measure(struct sev_vm *sev, uint8_t *measurement);
+void sev_vm_launch_finish(struct sev_vm *sev);
+
+#endif /* SELFTEST_KVM_SEV_H */
diff --git a/tools/testing/selftests/kvm/lib/x86_64/sev.c b/tools/testing/selftests/kvm/lib/x86_64/sev.c
new file mode 100644
index 000000000000..4a99862d62e6
--- /dev/null
+++ b/tools/testing/selftests/kvm/lib/x86_64/sev.c
@@ -0,0 +1,245 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Helpers used for SEV guests
+ *
+ * Copyright (C) 2021 Advanced Micro Devices
+ */
+
+#include <stdint.h>
+#include <stdbool.h>
+#include "kvm_util.h"
+#include "linux/psp-sev.h"
+#include "processor.h"
+#include "sev.h"
+
+#define PAGE_SHIFT		12
+#define PAGE_SIZE		(1UL << PAGE_SHIFT)
+
+struct sev_vm {
+	struct kvm_vm *vm;
+	int fd;
+	int enc_bit;
+	uint32_t sev_policy;
+};
+
+/* Common SEV helpers/accessors. */
+
+struct kvm_vm *sev_get_vm(struct sev_vm *sev)
+{
+	return sev->vm;
+}
+
+uint8_t sev_get_enc_bit(struct sev_vm *sev)
+{
+	return sev->enc_bit;
+}
+
+void sev_ioctl(int sev_fd, int cmd, void *data)
+{
+	int ret;
+	struct sev_issue_cmd arg;
+
+	arg.cmd = cmd;
+	arg.data = (unsigned long)data;
+	ret = ioctl(sev_fd, SEV_ISSUE_CMD, &arg);
+	TEST_ASSERT(ret == 0,
+		    "SEV ioctl %d failed, error: %d, fw_error: %d",
+		    cmd, ret, arg.error);
+}
+
+void kvm_sev_ioctl(struct sev_vm *sev, int cmd, void *data)
+{
+	struct kvm_sev_cmd arg = {0};
+	int ret;
+
+	arg.id = cmd;
+	arg.sev_fd = sev->fd;
+	arg.data = (__u64)data;
+
+	ret = ioctl(vm_get_fd(sev->vm), KVM_MEMORY_ENCRYPT_OP, &arg);
+	TEST_ASSERT(ret == 0,
+		    "SEV KVM ioctl %d failed, rc: %i errno: %i (%s), fw_error: %d",
+		    cmd, ret, errno, strerror(errno), arg.error);
+}
+
+/* Local helpers. */
+
+static void
+sev_register_user_region(struct sev_vm *sev, void *hva, uint64_t size)
+{
+	struct kvm_enc_region range = {0};
+	int ret;
+
+	pr_debug("%s: hva: %p, size: %lu\n", __func__, hva, size);
+
+	range.addr = (__u64)hva;
+	range.size = size;
+
+	ret = ioctl(vm_get_fd(sev->vm), KVM_MEMORY_ENCRYPT_REG_REGION, &range);
+	TEST_ASSERT(ret == 0, "failed to register user range, errno: %i\n", errno);
+}
+
+static void
+sev_encrypt_phy_range(struct sev_vm *sev, vm_paddr_t gpa, uint64_t size)
+{
+	struct kvm_sev_launch_update_data ksev_update_data = {0};
+
+	pr_debug("%s: addr: 0x%lx, size: %lu\n", __func__, gpa, size);
+
+	ksev_update_data.uaddr = (__u64)addr_gpa2hva(sev->vm, gpa);
+	ksev_update_data.len = size;
+
+	kvm_sev_ioctl(sev, KVM_SEV_LAUNCH_UPDATE_DATA, &ksev_update_data);
+}
+
+static void sev_encrypt(struct sev_vm *sev)
+{
+	const struct sparsebit *enc_phy_pages;
+	struct kvm_vm *vm = sev->vm;
+	sparsebit_idx_t pg = 0;
+	vm_paddr_t gpa_start;
+	uint64_t memory_size;
+
+	/* Only memslot 0 supported for now. */
+	enc_phy_pages = vm_get_encrypted_phy_pages(sev->vm, 0, &gpa_start, &memory_size);
+	TEST_ASSERT(enc_phy_pages, "Unable to retrieve encrypted pages bitmap");
+	while (pg < (memory_size / vm_get_page_size(vm))) {
+		sparsebit_idx_t pg_cnt;
+
+		if (sparsebit_is_clear(enc_phy_pages, pg)) {
+			pg = sparsebit_next_set(enc_phy_pages, pg);
+			if (!pg)
+				break;
+		}
+
+		pg_cnt = sparsebit_next_clear(enc_phy_pages, pg) - pg;
+		if (pg_cnt <= 0)
+			pg_cnt = 1;
+
+		sev_encrypt_phy_range(sev,
+				      gpa_start + pg * vm_get_page_size(vm),
+				      pg_cnt * vm_get_page_size(vm));
+		pg += pg_cnt;
+	}
+}
+
+/* SEV VM implementation. */
+
+static struct sev_vm *sev_vm_alloc(struct kvm_vm *vm)
+{
+	struct sev_user_data_status sev_status = {0};
+	uint32_t eax, ebx, ecx, edx;
+	struct sev_vm *sev;
+	int sev_fd;
+
+	sev_fd = open(SEV_DEV_PATH, O_RDWR);
+	if (sev_fd < 0) {
+		pr_info("Failed to open SEV device, path: %s, error: %d, skipping test.\n",
+			SEV_DEV_PATH, sev_fd);
+		return NULL;
+	}
+
+	sev_ioctl(sev_fd, SEV_PLATFORM_STATUS, &sev_status);
+
+	if (!(sev_status.api_major > SEV_FW_REQ_VER_MAJOR ||
+	      (sev_status.api_major == SEV_FW_REQ_VER_MAJOR &&
+	       sev_status.api_minor >= SEV_FW_REQ_VER_MINOR))) {
+		pr_info("SEV FW version too old. Have API %d.%d (build: %d), need %d.%d, skipping test.\n",
+			sev_status.api_major, sev_status.api_minor, sev_status.build,
+			SEV_FW_REQ_VER_MAJOR, SEV_FW_REQ_VER_MINOR);
+		return NULL;
+	}
+
+	sev = calloc(1, sizeof(*sev));
+	sev->fd = sev_fd;
+	sev->vm = vm;
+
+	/* Get encryption bit via CPUID. */
+	eax = 0x8000001f;
+	ecx = 0;
+	cpuid(&eax, &ebx, &ecx, &edx);
+	sev->enc_bit = ebx & 0x3F;
+
+	return sev;
+}
+
+void sev_vm_free(struct sev_vm *sev)
+{
+	kvm_vm_free(sev->vm);
+	close(sev->fd);
+	free(sev);
+}
+
+struct sev_vm *sev_vm_create(uint32_t policy, uint64_t npages)
+{
+	struct sev_vm *sev;
+	struct kvm_vm *vm;
+
+	/* Need to handle memslots after init, and after setting memcrypt. */
+	vm = vm_create(VM_MODE_DEFAULT, 0, O_RDWR);
+	sev = sev_vm_alloc(vm);
+	if (!sev)
+		return NULL;
+	sev->sev_policy = policy;
+
+	kvm_sev_ioctl(sev, KVM_SEV_INIT, NULL);
+
+	vm_set_memory_encryption(vm, true, true, sev->enc_bit);
+	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, 0, 0, npages, 0);
+	sev_register_user_region(sev, addr_gpa2hva(vm, 0),
+				 npages * vm_get_page_size(vm));
+
+	pr_info("SEV guest created, policy: 0x%x, size: %lu KB\n",
+		sev->sev_policy, npages * vm_get_page_size(vm) / 1024);
+
+	return sev;
+}
+
+void sev_vm_launch(struct sev_vm *sev)
+{
+	struct kvm_sev_launch_start ksev_launch_start = {0};
+	struct kvm_sev_guest_status ksev_status = {0};
+
+	/* Need to use ucall_shared for synchronization. */
+	ucall_init_ops(sev_get_vm(sev), NULL, &ucall_ops_halt);
+
+	ksev_launch_start.policy = sev->sev_policy;
+	kvm_sev_ioctl(sev, KVM_SEV_LAUNCH_START, &ksev_launch_start);
+	kvm_sev_ioctl(sev, KVM_SEV_GUEST_STATUS, &ksev_status);
+	TEST_ASSERT(ksev_status.policy == sev->sev_policy, "Incorrect guest policy.");
+	TEST_ASSERT(ksev_status.state == SEV_GSTATE_LUPDATE,
+		    "Unexpected guest state: %d", ksev_status.state);
+
+	sev_encrypt(sev);
+}
+
+void sev_vm_launch_measure(struct sev_vm *sev, uint8_t *measurement)
+{
+	struct kvm_sev_launch_measure ksev_launch_measure = {0};
+	struct kvm_sev_guest_status ksev_guest_status = {0};
+
+	ksev_launch_measure.len = 256;
+	ksev_launch_measure.uaddr = (__u64)measurement;
+	kvm_sev_ioctl(sev, KVM_SEV_LAUNCH_MEASURE, &ksev_launch_measure);
+
+	/* Measurement causes a state transition, check that. */
+	kvm_sev_ioctl(sev, KVM_SEV_GUEST_STATUS, &ksev_guest_status);
+	TEST_ASSERT(ksev_guest_status.state == SEV_GSTATE_LSECRET,
+		    "Unexpected guest state: %d", ksev_guest_status.state);
+}
+
+void sev_vm_launch_finish(struct sev_vm *sev)
+{
+	struct kvm_sev_guest_status ksev_status = {0};
+
+	kvm_sev_ioctl(sev, KVM_SEV_GUEST_STATUS, &ksev_status);
+	TEST_ASSERT(ksev_status.state == SEV_GSTATE_LUPDATE ||
+		    ksev_status.state == SEV_GSTATE_LSECRET,
+		    "Unexpected guest state: %d", ksev_status.state);
+
+	kvm_sev_ioctl(sev, KVM_SEV_LAUNCH_FINISH, NULL);
+
+	kvm_sev_ioctl(sev, KVM_SEV_GUEST_STATUS, &ksev_status);
+	TEST_ASSERT(ksev_status.state == SEV_GSTATE_RUNNING,
+		    "Unexpected guest state: %d", ksev_status.state);
+}
-- 
2.25.1

